Cover bolts replacement

[sweetalabama]

While changing the oil on my wife's 2020 XC40 yesterday I noticed that the lower engine cover bolts weren't replaced after the last oil change. One of the bolts is stuck and the Allen key head is stripped. I'm planning to replace them with stainless steel hex head bolts but I'm unsure about the exact size I need. Anybody here know these stuff and point me to the right direction? Thanks

 

[SparkyCrafter]

@sweetalabama gosh, It's frustrating when you find sloppy work like that! you can measure the diameter of the bolt shaft (without the threads) of one of the remaining good bolts

 

[sweetalabama]

@sweetalabama gosh, It's frustrating when you find sloppy work like that! you can measure the diameter of the bolt shaft (without the threads) of one of the remaining good bolts

These little things always the one casing problems jeez. Is this the only way? I dont wanna cause any more sloppy work.. lol

 

[BoxyButQuick]

Switching to stainless hex heads was a good idea, they're much simpler to handle. I think those bolts are M6, maybe around 20-22mm long. Just measure how deep yours need to go to be certain. Also, are the threads in the hole okay, or will you need to clean them up?

 

[RechargeRider]

Good call on the stainless hex heads, way easier to work with. And yeah, M6 at about 20-22mm sounds right. I'd double-check the depth just to be safe. Are your threads still clean, or do they need chasing?

 

[rafflesia2437]

I think the measurements provided above are somehow correct. but it's worth double checking with your manual or a dealer to confirm.

 

[skydr1ft]

@sweetalabama I agree with rafflesia, you can try to check the owner's manual. sometimes they list fastener sizes for common maintenance items.
Go to a site like VolvoPartsCounter or similar, enter your exact year and model, and search for "lower cover screw" or "undertray bolt." You'll likely see part number 31479387, which is listed as an M6x21.5. This is your best bet for confirming!